seabios-1.7.2 compatibility and code cleanup

* This version is fully compatible with SeaBIOS 1.7.2, I've also made some patch code cleanup to get rid of the things that are already implemented in the latest version, like 'bregs' and 'ahci_detect' stuff.

* Git command calls are removed from 'patch.sh'. Nobody would download tarball from Github or clone repo with git only to synchronize with the repo right after that. 'gitmodules' is removed for the same reason.

* 'patch.log' is removed from the repo (btw, why is it here?) Also, it would be better to remove 'acpi-slic.hex' since users should have their own, there is no reason to expose it here.

* Some README.markdown clarification.